Bleaching process



Patented Mar. 18, 1930 UNITED STATES PATENT OFFICE GUSTAV ADOLPH AND ALBERT PIETZSCH, OF HOELLRIEGELSKREUTH, NEAR MUNICH,

I GERMANY BLEAGHING PROCESS ;Io Drawing. Application filed March 11, 1927, Serial No. 174,691, and in Germany March 29, 1928.

Hitherto, active oxygen has been used for bleaching chiefly in the form of hydrogen peroxide-solutions, except with soaps and oils that are bleached by means of per-sulphate or benzoyl peroxide. Bleaching by perborate or similar agents is practically a hydrogen peroxide bleaching process, since these chemical compositions split off hydrogen peroxide when dissolved.

Now, it was found, that a number of articles can be bleached to advantage by mixtures of hydrogen peroxide and percompounds, that do not split off hydrogen peroxide in the presence of water, as e. g. persulphates or benzoyl peroxide. It might have been expected, that such mixtures would decompose each other in a bleaching process, but such is not the case, rather a stronger bleaching eiiect taking place than with the employment of the single components. To obtain a more or less strong bleaching effect indifferent liquids, e. g. alcohol, may be added to the bleaching solutions. The bleaching baths, according to the requirements, may be either alkaline or neutral or acid.

If per-salts are used in an acid solution the same bleaching efl'ect results as with the addition of hydrogen peroxide, since hydrogen peroxide is' split off from the percompounds by the acid. so that this case forms aspecial case of the general process only. The bleaching eflect of such mixtures is so stron that they will bleach even in the cold, quick y and efiiciently within a few hours.

Example -phate of ammonia, feat-hers or hair may be leached and become bright within a few hours without affecting the article to be bleached. The bleaching efiect is accelerated and increased in many cases by ex osing the article to be bleached to the light uring the bleaching process, whereby the bleaching process may take place either in the bleaching bath itself or in the open air, in the latter case after the article has been soaked with the above mentioned solutions.

W'e declare, what we claim is:

1. I11 the process of bleaching, the step which consists in treating the articles to be bleached in abath containing hydrogen peroxide and a persulphate.

2. As a new article of manufacture, a bleaching bath comprising hydrogen peroxide and a persulphate.

In testimony whereof we hereunto allix our signatures.

DR. GUSTAV ADOLPH. ALBERT PIETZSCH. 

